The longest geological cycle identified is described as about 600 million years in "Megacycles", the proceedings of a geological conference, Edited by G Williams. However Prof S Afanasiev of Moscow has determined the cycle very accurately to be 586.24 million years using his Nanocycles Method.
It so happens that cosmologists, Broadhurst, T.J., Ellis, R.S., Koo, D.C. & Szalay (Nature 343, p 726) have observed regular mega-walls of galaxies at spacings that they describe as 128 Mpc/h,...